The present invention generally relates to video coding, and more particularly to methods and apparatus for error-resilient video coding.
Compression techniques in image and video coding have been developed with the assumption of a reliable and noise free transport. In current video coding standards (e.g., MPEG-1, MPEG-2, and H.263), a block-based motion estimation and compensation scheme has been adopted that is combined with Discrete Cosine Transform (DCT) coding of the motion prediction error. In order to maximize coding efficiency, motion information and the DCT coded motion prediction error are entropy coded using variable length codes. This results in a bit stream that is vulnerable to channel errors, and the quality of the reconstructed video may be substantially degraded unless redundant information or an error-correction method is applied to the bit stream.
Techniques have been introduced to mitigate the effects of channel errors, including traditional channel coding and signal recovery. For example, forward error correction, error control coding, automatic retransmission request, signal reconstruction and error concealment have been introduced to mitigate the effects of channel errors. (See, Y. Wang and Q. Zhu, xe2x80x9cError Control and Concealment for Video Communication: A Review,xe2x80x9d Proceedings of the IEEE, Vol. 812, May 1998, which is hereby incorporated by reference.) Although these error-correction techniques provide satisfactory minimization of the effects that channel noise has on coded data under most, but not necessarily all, operating circumstances, the techniques generally introduce complexity and delay in the image coding process and apparatus. Moreover, the addition of redundant information to the compressed video data typically reduces the compression efficiency.